Characteristic Analysis And Modeling Of Wireless Communication Channels In Railway 5G Dedicated Network

With the booming development of high-speed railway in China,the corresponding railway wireless communication system is also faced with the need of update,and 5G has been used as the primary system of the new generation of mobile communication.Being tasked with services such as train control,dispatch command information transmission,and multimedia dispatch communication（MCX）,the railway 5G dedicated network is an essential means to ensure traffic safety,enhance railway transportation efficiency,and improve service quality..Accurate channel model serves as the foundation for realizing railway 5G dedicated network communication system,which needs to perform data acquisition,data analysis by a large number of actual tests for parameter extraction and modeling.Currently,there are few channel model results under the railway 5G dedicated network.Hence,this paper has conducted the channel measurement,analysis and modeling of the5 G communication system of 2.6GHz frequency railway,established large-scale channel models,analyzed and simulated the small-scale channel feature acquisition algorithm.The following is the main work and innovation achievements:（1）Channel modeling methods and analysis of high-speed channel characteristics.This part introduces the channel modeling methods commonly used in the study of wireless channel characteristics,and analyzes the channel characteristics of existing models and those in high-speed operating environments,thereby laying the theoretical foundation for the subsequent measurement and modeling of railway 5G communication system channel.（2）Research on channel measurement system.This part introduces the small-scale and large-scale channel measurement systems used in this paper,and focuses on the study of the transmission sequence of small-scale measurement systems.Through simulating PN codes of different types and lengths,it selects the most suitable transmission sequence of railway measurement system based on the simulation results and the railway characteristics.（3）Large-scale channel modeling.For the railway 5G dedicated network,this paper selects SS-RSRP as the field strength detection indicator,and collects data at the operation speed of 120 km/h to modify the 3GPP TR 38.901 model.Meanwhile,the data under different PCIs are averaged and equally spaced,and the Savitzky-Golay method is employed for the moving average filtering,and the path loss formula of the propagation model is fitted according to the gradient descent method.Finally,RMSE and MAPE are used to verify the accuracy of the fitting formula.The results indicate that the modified results are more accurate than that of the TR 38.901 model,the model has enhanced generalization capacity and is more in line with the measured data,which improves the applicability in the scenario of railway 5G dedicated network.（4）Acquisition algorithm analysis of small-scale channel characteristics.This part simulates three algorithms,namely,MUSIC,Esprit,and SAGE.Among them,the SAGE algorithm is mainly used for the multipath parameter extraction.According to the results,the algorithm can effectively extract the multipath channel parameters,which verifies its correctness and applicability.It can effectively extract small-scale channel characteristic parameters of railway 5G dedicated network.